Four Phases or states of Matter Solid Liquid Gas Plasma

Solids Constant volume Constant shape Atoms or molecules are well ordered into a crystal lattice for most materials Particles have VIBRATIONAL motion ONLY Exceptions Glass which is a very slow flowing liquid Amorphous solids have no crystal structure

Liquids Constant volume Variable shape Incompressible Atoms or molecules loosely attracted to its neighbors, but in close proximity which allows fluid particles Translational (place to place) motion

Gases Variable volume Variable shape VERY Compressible Atoms or molecules are widely separated and have little interaction with each other aside from collisions resulting from their Translational motion

Water is strange! Water expands as it forms a solid. This causes the density of ice to be less than liquid water and, therefore, ice floats in liquid water. Note the structure of liquid water (left) and ice (right). Notice the greater space in the organized crystalline ice structure which is the cause of the expansion. Germanium also does this.

Plasma Temperature is so high that negative electrons are separated from their positively charged atomic nuclei No molecules exist Particles are electrically charged Found in Sun, stars, neon bulbs, lightning bolts and Fusion reactors.

Direction of Heat Transfer Heat ALWAYS travels from a higher concentration of energy (high temperature) to a lower concentration of energy (low temperature).

Changing Phases or States For elements, all four states are possible. Compounds can be only solids, liquids or gases PHASE CHANGES occur when energy content changes ENERGY: Plasma>Gas>Liquid>Solid Energy content is the cause of the differences between states or phases at the particle level

Molecular velocity determines TEMPERATURE and STATE Slow moving molecules Means cooler material If cool enough, particle attractions overcome motion and they begin to stick together(freezing) Fast moving molecules Means warmer material If warm enough, particles have enough energy to leave the solid surface to liquid (melting) or the liquid surface to become gaseous (vaporizing)

6 Phase Changes Freezing (liquid to solid) Melting(solid to liquid) Vaporization (evaporation or boiling)(liquid to gas) Condensation(gas to liquid) Sublimation(solid to gas- skip liquid) Deposition(gas to solid- skip liquid)

Melting and Freezing Changes between liquid and solid Freezing is the opposite of melting Melting - Attractions between solid particles break when energy is added and vibrations increase until they escape into liquid state Freezing - Particles move slowly enough that attractions can pull particles together to form solid

Vaporizing Liquid particles break the attractions of neighboring particles and travel up into the gaseous layer Evaporation- only particles near the surface have enough energy (traveling fast enough) to break the attractions Boiling – particles throughout the liquid are traveling fast enough to form bubbles with higher pressure than outside conditions. Boiling Point

Evaporation – occurs only from the surface

Evaporation-surface particles only Only particles near the surface have enough energy to become a gas Liquid particles take energy from the liquid to enter gaseous state which cools the liquid The gas layer can also cool because of the influx of slower moving gas particles

Boiling –any particle in the sample has enough energy to travel fast enough to exit the liquid phase

Evaporation (are you sure?)

Condensation

The opposite of evaporation Interaction of high energy particles with a cooler surface to form liquid Evaporation and Condensation occur usually on the SURFACE Gas particles release heat to rejoin the liquid (Exothermic)

Sublimation Particles going directly from solid state to gaseous state. Dry Ice is a good example: Don’t touch, use gloves -78˚C - Sublimation point which is 115˚colder than you Extended contact = Frost bite Dry Ice NEVER melts Solids that smell usually do so because of Sublimation: Chocolate particles enter your nose

Deposition Hot gaseous atoms forming a layer of solid on a cooler surface: manmade Diamonds are gaseous Carbon on a seed crystal Can be used to form a layer of thin expensive metal on cheap metal base

Energy and Phase Change T Time Adding heat at a constant rate Melting Boiling

Viscosity is related to flow rate Low Viscosity – material can flow rapidly Water and Alcohol have low viscosity High Viscosity – material flows slowly Motor oil, lava, molasses, honey all have high viscosity

Pressure

Boyle’s Law Pressure vs Volume Relationship P1 x V1 = P2 x V2 Original New Decrease the volume of a gas causes a higher pressure. Increase the Volume of a gas causes a lower pressure. Indirect Relationship

Boyle’s Law Sample Problem

Charles’ Law = Volume vs Temperature

Charles’ Law Sample problem

Graphing Reasons and Rules Purpose: To find how variables relate X-axis: Independent variable (manipulated) Y-axis: Dependent variable (responding) Slope = rise/run = rate of change Use = Predicting values that were previously unknown Graphs MUST have TITLES Graphs MUST have Labels X-axis Independent Y-axis Dependent

Graphing Outcomes Directly proportional : A is up & B is up Indirectly proportional : A is up but B is down Straight line graph: varying at a constant rate Curved line graph: varying at a changing rate